package the.one.base.widge.datePicker;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.Paint.FontMetricsInt;
import android.graphics.Paint.Style;
import android.os.Handler;
import android.os.Message;
import androidx.annotation.ColorInt;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

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//    ┃　　　┃                  神兽保佑
//    ┃　　　┃                  永无BUG！
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/**
 * @author The one
 * @date 2019/7/25 0025
 * @describe TODO
 * @email 625805189@qq.com
 * @remark
 */
public class DatePickerView extends View {

        private Context context;
        /**
         * 新增字段 控制是否首尾相接循环显示 默认为循环显示
         */
        private boolean loop = true;
        /**
         * text之间间距和minTextSize之比
         */
        public static final float MARGIN_ALPHA = 2.8f;
        /**
         * 自动回滚到中间的速度
         */
        public static final float SPEED = 10;
        private List<String> mDataList;
        /**
         * 选中的位置，这个位置是mDataList的中心位置，一直不变
         */
        private int mCurrentSelected;
        private Paint mPaint, nPaint;
        private float mMaxTextSize = 80;
        private float mMinTextSize = 40;
        private float mMaxTextAlpha = 255;
        private float mMinTextAlpha = 120;
        private int mViewHeight;
        private int mViewWidth;
        private float mLastDownY;
        /**
         * 滑动的距离
         */
        private float mMoveLen = 0;
        private boolean isInit = false;
        private boolean canScroll = true;
        private onSelectListener mSelectListener;
        private Timer timer;
        private MyTimerTask mTask;

        private Handler updateHandler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                if (Math.abs(mMoveLen) < SPEED) {
                    mMoveLen = 0;
                    if (mTask != null) {
                        mTask.cancel();
                        mTask = null;
                        performSelect();
                    }
                } else {
                    // 这里mMoveLen / Math.abs(mMoveLen)是为了保有mMoveLen的正负号，以实现上滚或下滚
                    mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED;
                }
                invalidate();
            }
        };

    public DatePickerView(Context context, AttributeSet attrs) {
            super(context, attrs);
            this.context = context;
            init();
        }

        public void setOnSelectListener(onSelectListener listener) {
            mSelectListener = listener;
        }

        private void performSelect() {
            if (mSelectListener != null) {
                mSelectListener.onSelect(mDataList.get(mCurrentSelected));
            }
        }

        public void setData(List<String> data) {
            mDataList = data;
            mCurrentSelected = data.size() / 4;
            invalidate();
        }

        /**
         * 选择选中的item的index
         * @param selected the selected index
         */
        public void setSelected(int selected) {
            mCurrentSelected = selected;
            if (loop) {
                int distance = mDataList.size() / 2 - mCurrentSelected;
                if (distance < 0) {
                    for (int i = 0; i < -distance; i++) {
                        moveHeadToTail();
                        mCurrentSelected--;
                    }
                } else if (distance > 0) {
                    for (int i = 0; i < distance; i++) {
                        moveTailToHead();
                        mCurrentSelected++;
                    }
                }
            }
            invalidate();
        }

        /**
         * 选择选中的内容
         * @param mSelectItem selected item
         */
        public void setSelected(String mSelectItem) {
            for (int i = 0; i < mDataList.size(); i++) {
                if (mDataList.get(i).equals(mSelectItem)) {
                    setSelected(i);
                    break;
                }
            }
        }

        private void moveHeadToTail() {
            if (loop) {
                String head = mDataList.get(0);
                mDataList.remove(0);
                mDataList.add(head);
            }
        }

        private void moveTailToHead() {
            if (loop) {
                String tail = mDataList.get(mDataList.size() - 1);
                mDataList.remove(mDataList.size() - 1);
                mDataList.add(0, tail);
            }
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            mViewHeight = getMeasuredHeight();
            mViewWidth = getMeasuredWidth();
            // 按照View的高度计算字体大小
            mMaxTextSize = mViewHeight / 7f;
            mMinTextSize = mMaxTextSize / 2.2f;
            isInit = true;
            invalidate();
        }

        private void init() {
            timer = new Timer();
            mDataList = new ArrayList<>();
            //第一个paint
            mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mPaint.setStyle(Style.FILL);
            mPaint.setTextAlign(Align.CENTER);
            //第二个paint
            nPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            nPaint.setStyle(Style.FILL);
            nPaint.setTextAlign(Align.CENTER);
            setColors(0xFF333333, 0xFF59B29C);
        }

        /**
         *
         * @param textColor 未选中的文字颜色
         * @param selectedTextColor 选中的文字颜色
         */
        public void setColors(@ColorInt int textColor, @ColorInt int selectedTextColor){
            nPaint.setColor(textColor);
            mPaint.setColor(selectedTextColor);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);
            // 根据index绘制view
            if (isInit) {
                drawData(canvas);
            }
        }

        private void drawData(Canvas canvas) {
            // 先绘制选中的text再往上往下绘制其余的text
            float scale = parabola(mViewHeight / 4.0f, mMoveLen);
            float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;
            mPaint.setTextSize(size);
            mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
            // text居中绘制，注意baseline的计算才能达到居中，y值是text中心坐标
            float x = (float) (mViewWidth / 2.0);
            float y = (float) (mViewHeight / 2.0 + mMoveLen);
            FontMetricsInt fmi = mPaint.getFontMetricsInt();
            float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));

            canvas.drawText(mDataList.get(mCurrentSelected), x, baseline, mPaint);
            // 绘制上方data
            for (int i = 1; (mCurrentSelected - i) >= 0; i++) {
                drawOtherText(canvas, i, -1);
            }
            // 绘制下方data
            for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++) {
                drawOtherText(canvas, i, 1);
            }
        }

        /**
         * @param position 距离mCurrentSelected的差值
         * @param type     1表示向下绘制，-1表示向上绘制
         */
        private void drawOtherText(Canvas canvas, int position, int type) {
            float d = MARGIN_ALPHA * mMinTextSize * position + type * mMoveLen;
            float scale = parabola(mViewHeight / 4.0f, d);
            float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;
            nPaint.setTextSize(size);
            nPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
            float y = (float) (mViewHeight / 2.0 + type * d);
            FontMetricsInt fmi = nPaint.getFontMetricsInt();
            float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));
            canvas.drawText(mDataList.get(mCurrentSelected + type * position),
                    (float) (mViewWidth / 2.0), baseline, nPaint);
        }

        /**
         * 抛物线
         *
         * @param zero 零点坐标
         * @param x    偏移量
         */
        private float parabola(float zero, float x) {
            float f = (float) (1 - Math.pow(x / zero, 2));
            return f < 0 ? 0 : f;
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            switch (event.getActionMasked()) {
                case MotionEvent.ACTION_DOWN:
                    doDown(event);
                    break;

                case MotionEvent.ACTION_MOVE:
                    mMoveLen += (event.getY() - mLastDownY);
                    if (mMoveLen > MARGIN_ALPHA * mMinTextSize / 2) {
                        if (!loop && mCurrentSelected == 0) {
                            mLastDownY = event.getY();
                            invalidate();
                            return true;
                        }
                        if (!loop) {
                            mCurrentSelected--;
                        }
                        // 往下滑超过离开距离
                        moveTailToHead();
                        mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;
                    } else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2) {
                        if (mCurrentSelected == mDataList.size() - 1) {
                            mLastDownY = event.getY();
                            invalidate();
                            return true;
                        }
                        if (!loop) {
                            mCurrentSelected++;
                        }
                        // 往上滑超过离开距离
                        moveHeadToTail();
                        mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;
                    }
                    mLastDownY = event.getY();
                    invalidate();
                    break;

                case MotionEvent.ACTION_UP:
                    doUp();
                    break;
            }
            return true;
        }

        private void doDown(MotionEvent event) {
            if (mTask != null) {
                mTask.cancel();
                mTask = null;
            }
            mLastDownY = event.getY();
        }

        private void doUp() {
            // 抬起手后mCurrentSelected的位置由当前位置move到中间选中位置
            if (Math.abs(mMoveLen) < 0.0001) {
                mMoveLen = 0;
                return;
            }
            if (mTask != null) {
                mTask.cancel();
                mTask = null;
            }
            mTask = new MyTimerTask(updateHandler);
            timer.schedule(mTask, 0, 10);
        }

        class MyTimerTask extends TimerTask {
            Handler handler;

            public MyTimerTask(Handler handler) {
                this.handler = handler;
            }

            @Override
            public void run() {
                handler.sendMessage(handler.obtainMessage());
            }
        }

        public interface onSelectListener {
            void onSelect(String text);
        }

        public void setCanScroll(boolean canScroll) {
            this.canScroll = canScroll;
        }

        @Override
        public boolean dispatchTouchEvent(MotionEvent event) {
            return canScroll && super.dispatchTouchEvent(event);
        }

        /**
         * 控制内容是否首尾相连
         * @param isLoop loop scroll or not
         */
        public void setIsLoop(boolean isLoop) {
            loop = isLoop;
        }

    }